AUTOIMMUNE AETIOLOGY FOR MYASTHENIC (EATON-LAMBERT) SYNDROME

224

Requests for reprints should be addressed to B. A. C., Infectious Disease Division, Nassau Hospital, 259 First Street, Mineola, New York 11501. REFERENCES 1. Hanshaw

JB, Schultz FW, Melish MM, Dudgeon JA. Congenital cytomegalovirus infection. Ciba Fdn Symp 1971; 10: 23-43. 2. Monif GRG, Egan EA, Held B. The correlation of maternal cytomegalovirus infection during varying stages in gestation with neonatal involvement. J Pediatr 1972; 80: 17-20.

Montplaisir S Latency

3.

Microbiol

Lang DJ.

4.

and activation

of cytomegalovirus

in

man

and mice. Can J

1979; 25: 261-66.

The

epidemiology of cytomegalovirus infections: interpretation of recent Krugman S,

observations. Infections of the fetus and the newborn infant. In: Gershon AA, eds. New York: Alan R. Liss, Inc., 1975: 35-54.

Huang ES, Alford CA, Reynolds DW, Stagno S, Pass RF. Molecular epidemiology of cytomegalovirus infections in women and their infants. N Engl J Med 1980; 17:

5.

958-62.

Lang DJ, Cheung KS, Schwartz JN, Daniels CA, Harwood SE. Cytomegalovirus replication and the host immune response Yale J Biol Med 1976, 49: 45-58. 7. Schmitz H, Kampa D, Doerr HW, Luthardt DT, Hillemanns HG, Wurtele A. IgM antibodies to cytomegalovirus during pregnancy. Arch Virol 1977, 55: 177-84. 8. Reynolds DW, Stagno S, Hosty TS, Tiller M, Alford CA, Jr. Maternal cytomegalovirus excretion and perinatal infection. N Engl J Med 1973; 289: 1-5. 9. Hayes K, Danks DM, Gibas H, Jack I. Cytomegalovirus in human milk. N Engl J Med

6.

1972; 287: 177-78. 10.

Lang DJ. Cytomegalovirus immunization- status, prospects, and problems. Rev Infect

Dis 1980, 2: 449-57. 1 1. Hanshaw JB. Congenital cytomegalovirus infection: a fifteen year perspective. J Infect Dis 1971; 123: 555-61. 12. Stagno S, Reynolds DW, Huang ES, Thames SD, Smith RJ, Alford CA. Congenital 1977; 296: 1254-57. cytomegalovirus infection. N Engl Med J 13. Gehrz RC, et al. Specific cell-mediated immune defect in congenital cytomegalovirus

infection. Lancet 1977; i: 811-12. 14. Kibrick S, Loria RM Rubella and cytomegalovirus. Pediat Clin N Am 1974; 21: 513-26. 15. American Academy of Pediatrics. Report of the Committee on Infectious Diseases. 18th ed, Evanston, 1977: 124. 16. Remington JS, Klein JD, eds. Infectious disease of the foetus and newborn infant. Philadelphia: WB Saunders, 1976:119.

AUTOIMMUNE AETIOLOGY FOR MYASTHENIC (EATON-LAMBERT) SYNDROME BETHAN LANG DENNIS WRAY

JOHN NEWSOM-DAVIS

fatiguability, sometimes associated with carcinoma. The nonneoplastic form of the illness may develop in childhood,2 and patients have been followed up3 for twenty-five years with no signs-of tumour development.3 In both forms of the disease the underlying disorder is presynaptic, in contrast to the postsynaptic disorder in myasthenia gravis. Electromyography typically reveals a very small initial compound muscle action potential (MAP) which progressively increases with nerve stimulation rates above 10/s.4 In vitro electrophysiological studies have shown a defect in the impulse-evoked release of acetylcholine (ACh) nerve terminal. The amount of ACh in each is quantum normal, but the number of quanta released with each impulse is greatly reduced and increases with repetitive

from the

stimulation.5 Postsynaptic acetylcholine receptors (AChR) are normal in number and antibodies to AChR are absent,6 The cause of the two forms of the disease is unknown. Production of a biologically active peptide that interferes with neuromuscular transmission has been suggested in the neoplastic form of the disease.5 In non-tumour cases associated disorders, believed to have an immunological basis, have been reported.7 We present preliminary evidence, based on clinical and experimental studies, that supports an autoimmune origin for MYS.

Patients, Materials, and Methods Patients 1 and 2 had associated autoimmune disease but no evidence of carcinoma, while patient 3 had carcinoma of the bronchus (table I). All three had proximal muscle weakness principally affecting the legs. In addition, patient 3 had mild truncal ataxia. Reflexes were depressed (patient 3) or absent (patients 1 and 2), but could be elicited in the biceps after voluntary contraction for 10 s. Repeated ulnar nerve stimulation with recording electrodes on abductor digiti minimi showed abnormalities in MAP characteristic of MYS (table I).

Immunological

ANGELA VINCENT

Treatment

Plasma exchange was carried out with a Haemonetics 30 cell separator. The volume of plasma removed at each exchange was 55 ml/kg body weight, and 50% of this volume was replaced by plasma

Departments of Neurological Science and Pharmacology, Royal Free Hospital School of Medicine, London NW3

fraction (PPF) or ’Buminate’. Immunosuppressive drug consisted of azathioprine (2 - 5 mg/kg body weight) and alternate day prednisolone (60-100 mg).

protein

treatment

NICHOLAS MURRAY

’

Department of Clinical Neurophysiology, National Hospital for Nervous Diseases, London WC1

Passive

Transfer in Mice

The

Summary

The

myasthenic (Eaton-Lambert)

syn-

drome, associated with carcinoma of the bronchus in one patient and with immunological disorders in two others, improved after plasma exchange—observations supported by electromyographic evidence in two cases. Prednisolone and azathioprine treatment led to almost complete remission in one of the non-neoplastic cases and to improvement in the other. The IgG fraction of plasma from all three patients, injected daily (10 mg) into mice for 37-77 days, significantly reduced the initial compound muscle action potential and the quantal content of the end-plate potential measured in the diaphragm, when compared with control human IgG. These results indicate that an IgG autoantibody, binding to nerve terminal determinants, may be responsible for the disorder of neuromuscular transmission in the myasthenic syndrome, and that immunosuppressive drugs may be useful in treating the nonneoplastic form of the disease.

IgG fraction was extracted from plasma, obtained at plasma exchange, by the ’Rivanol’ (ethacridine lactate)/ammonium sulphate method.9 Pooled human plasma was used as control. 10 mg IgG from patients 1 and 3 was in each case daily injected intraperitoneally into 2 mice, and IgG from patient 2 was injected into 4 mice (BKTO strain), and control IgG was similarly injected into 5 mice. Cyclophosphamide (300 mg/kg) was injected on day one TABLE I-CLINICAL FEATURES

Introduction Lambert and his

syndrome (MYS)

colleaguesl with

have described a myasthenic proximal muscle weakness and

*Measured in abductor digiti minimi. t Measured 3 s after 15s maximum voluntary contraction.

225 the response to the foreign immunoglobulin. At the end of the experiment, repeated stimulation was done under anaesthesia with a needle electrode close to the sciatic nerve at the sciatic notch, and MAPs were recorded from surface electrodes over the small foot muscles. The diaphragm, with phrenic nerves intact, was then removed from the anaesthetised animal. One half was immediately placed in well-oxygenated Krebs solution at 22-26 °C. Intracellular voltage recordings were made with glass microelectrodes. Endplates were localised by microscopy and by the finding of end-plate potentials with fast rise-times. The phrenic nerve was stimulated with wire electrodes, and the quantal content for normal calcium and magnesium concentrations was measured in the presence of tubocurarine using Poisson statistics (variance method). 1 AChR content in the other half-diaphragm was determined by tI measurement of the number of 125I-a-bungarotoxin binding sites. to suppress

Results

.

Plasma Exchange and Immunosuppressive Drug Treatment Patient I had shown only a small clinical and electromyographic response to pyridostigmine (’Mestinon’) (120 mg 3-hourly) over three months. In October, 1979, she underwent a course of 15 daily plasma exchanges over three weeks, followed by another three-week course of 5 daily exchanges three weeks later. Clinical and electromyographic evidence of improvement was apparent after the first ten exchanges, but disappeared within two weeks of completion of the first course of exchanges (see figure). Six months later we started immunosuppressive drug treatment (prednisolone 60 mg on alternate days, azathioprine 2-55 mg/kg). Improvement was evident by two months and has been maintained (figure). Patients 2 and 3 both showed an increase in muscle strength, after 12 exchanges over eighteen days and 9 exchanges over eleven days, respectively. -This was not accompanied by clear electromyographic improvement in patient 2, but patient 3 showed a more than twofold increase in the initial MAP in abductor digiti minimi. Subsequent immunosuppressive drug treatment (prednisolone 100 mg on alternate days, azathioprine 2’55 mg/kg) in patient 2 was associated with progressive but slow improvement. Four months after the start of treatment exercise tolerance had increased, as had muscle strength, and the initial MAP had increased from 0-4mV to 1’6mV. In patient 3,

TABLE II-PASSIVE TRANSFER

Serum human IgG levels were similar in test and control mice and were within the normal range in man. *Small foot muscles (n = number of observations).

fdiaphragm (n =number of end-plates). t. Diaphragm (n = number of observations). §p<0-001; Dp<0-05; Student’s t test one-tailed.

immunosuppressive drugs were stopped after three months signs of superior venacava obstruction developed. During this time there was no evidence of improvement in muscle strength. Passive Transfer in Mice None of the mice showed obvious muscle weakness during the period of daily injections. At the end of the experiment, however, MAPs were significantly reduced in the test mice compared with MAPs in mice injected for the same period with control IgG (table II). Abnormal neuromuscular transmission was demonstrated by in vitro The studies. content of the endelectrophysiological quantal reduced in the was test animals plate potential significantly The effect was least pronounced, although (table II). significant, in mice injected with IgG from patient 1. These animals received only 37 injections compared with 51-77 in when

the other two cases and in the controls. The number of endplate AChRs was not significantly reduced, as measured by

a-bungarotoxin binding (table II). Discussion We have presented several lines of evidence which indicate autoimmune basis for the non-neoplastic form of MYS. Both our cases with this form of the disease had associated immunological disorders. This has been reported in a few other cases of MYS which have occurred with pernicious anaemia and hypothyroidism,7 rheumatoid arthritis,l2 and thyrotoxicosis.13 We have also studied three MYS patients who had pernicious anaemia, thyrotoxicosis, and coeliac disease, respectively. Electrophysiological studies have sometimes indicated the coexistence of myasthenia gravis and MYS,14 and MYS has occurred with malignant thymoma. 15 The response to plasma exchange in this study implicates a humoral factor, which could be an autoantibody. The response, most evident in patient 1, showed a much longer time lag than the response to exchange in myasthenia gravis where improvement can occur within one or two days of the first exchange, probably because new AChR is synthesised free of antibody. 16 In MYS, therefore, the putative factor may be binding to nerve terminal determinants which have a lower rate of turnover than the AChR, and this may account for the fact that Kranz et al. did not observe a response in a patient with MYS who underwent 6 exchanges over thirty an

The effects of

pyridostigmine (120 mg 3-hourly), repeated daily plasma exchange (PE), prednisolone (60 mg alternate days), and azathioprine (2,5 mglkg), on the initial amplitude of the MAP evoked in abductor digiti minimi by ulnar nerve stimulation in patient 1.

days.17 The remission in patient 1 and improvement in patient 2 after drug treatment also favour an autoimmune basis for the

226

non-neoplastic form of MYS.

We have since seen great clinical and electromyographic improvement with this treatment in two other cases of MYS, a 60-year-old woman and a 26-year-old man. Immunosuppressive drugs have not often been used to treat MYS, but response to steroids has been reported.18,19 The passive transfer of the physiological abnormality to mice by the injection of MYS IgG fraction further supports an autoimmune basis for the disease and suggests that an autoantibody binding to the nerve terminal may be implicated in the disorder of neuromuscular transmission. The reduction in the quantal content by 30-50% was less than that in the spontaneous disease (up to 90%)," and electromyographic abnormalities appeared to take much longer to develop than those after injection of myasthenia gravis IgG into mice.20 This could be due to the poorer crossreactivity of the IgG with mouse nerve terminal determinants, which may also explain why MYS serum did not have an effect when applied in vitro.17 On the other hand, the slow time course of the passively transferred disease and the time lag of the response to plasma exchange could both be attributed to slow turnover of putative presynaptic binding sites. The IgG fraction of the patient with neoplastic MYS (patient 3) could also passively transfer the disorder. This may mean that autoantibody to a tumour neoantigen was cross-reacting with determinants on the nerve terminal. However, the possibility that the IgG fraction might contain additional peptides secreted by the tumour that were mediating the effect, has not yet been excluded. Ishikawa et al.21 have extracted a substance from tumour material obtained from a MYS patient which reduced end-plate potential amplitudes in frog muscle. Our proposed autoimmune basis for the non-neoplastic form of MYS has implications for treatment. Existing pharmacological treatment is unsatisfactory. Pyridostigmine is relatively ineffective. The side-effects of guanidine22,23 and of the newer preparation, 4-aminopyridine,24,25 are serious and even life-threatening. Moreover, if MYS is of autoimmune origin these drugs can only provide symptomatic relief. Although immunosuppressive drug treatment is not without risk, our initial observations on its efficacy in this condition are encouraging. We thank Miss E. Goodger, SRN, and Dr L. Loh for help with plasma exchanges; Mr M. Gwilt for help with physiological studies; and Dr John Durston, Prof. P. K. Thomas, and Dr P. Kennedy for referring patients. This work was supported by the Medical Research Council. Requests for reprints should be addressed to J. N.-D., Department of Neurological Science, Royal Free Hospital, Pond Street, London NW3 2QG. REFERENCES 1 Lambert EH, Rooke ED, Eaton LM, Hodgson CH. Myasthenic syndrome occasionally associated with bronchial neoplasm Neurophysiologic studies In: Viets HR, ed. Myasthenia gravis. Springfield, Ill. Charles C Thomas, 1961: 362-410. 2 Chelmicka-Schorr E, Bernstein LP, Zurbrugg EB, Huttenlocher PR. Eaton-Lambert syndrome in a 9-year old girl Arch Neurol 1979, 36: 572-74 3 Brown JC, Johns RJ Diagnostic difficulties encountered in the myasthenia syndrome sometimes associated with carcinoma. J Neurol Neurosurg Pychiat 1974; 37: 1214-24. 4 Elmqvist D, Lambert EH Detailed analysis of neuromuscular transmission in a patient with the myasthenic syndrome sometimes associated with bronchogenic carcinoma. Mayo Clin Proc 1968; 43: 689-713 5. Lambert EH, Elmqvist D Quantal components of end-plate potentials in the myasthenic syndrome Ann NY Acad Sci 1971; 183: 183-99 6. Lindstiom JM, Lambert EH. Content of acetylcholine receptor and antibodies bound to receptor in myasthenia gravis, experimental autoimmune myasthenia gravis and Eaton-Lambert syndrome. Neurology 1978, 28: 130-38. 7 Guttmann L, Crosby TW, Takamori M, Martin JD. The Eaton-Lambert syndrome and autoimmune disorders Am J Med 1972, 53: 354-56 8. Newsom-Davis JM Plasma exchange in myasthenia gravis Plasma Therapy 1979; 1: 17-31.

Preliminary Communications RESPONSE OF CUTANEOUS T CELL LYMPHOMA TO THERAPY WITH HYBRIDOMA MONOCLONAL ANTIBODY RICHARD A. MILLER

RONALD LEVY

Howard Hughes Medical Institute and Division of Oncology, Department of Medicine, Stanford University, Stanford, California 94305, U.S.A.

A murine hybridoma monoclonal anti-Tcell antibody was given to a patient with advanced cutaneous T cell lymphoma. The patient tolerated seventeen treatment courses over ten weeks without symptoms of toxicity. Each treatment caused a reduction in circulating T cells which reached a stable level after two weeks of therapy. Antigenic modulation was observed after each treatment but was fully reversed within three to four days; therefore the treatment was given twice weekly. Monoclonal antibody produced a striking clinical response in skin, lymph nodes, and blood but complete remission was not achieved. Since the remaining disease was antigen positive, failure to eradicate all tumour cells was not a result of immunoselection. At no time did the patient show an antimouse immune response.

Summary

INTRODUCTION

PASSIVE antibody therapy for cutaneous T cell lymphomas (CTCL) has attracted much attention because these tumours express normal T cell differentiation antigens to which heterologous antisera are readily available. 1,2 In.one study, treatment ofa patient with antithymocyte globulin resulted in an impressive remission of skin and lymph-node disease.3

9. 10

Horejsi J, Smetana R. The isolation of gamma-globulins from blood serum by Rivanol Acta Med Scand 1956; 155: 65-70 Del Castillo J, Katz B. Quantal components of the end-plate potential J Physiol 1954,

124: 560-73. 11 Green DPL, Miledi R, Vincent A Neuromuscular transmission after immunisation against acetylcholine receptors. Proc Roy Soc B 1975; 189: 57-68. 12 Takamori M. Caffeine, calcium and Eaton-Lambert syndrome Arch Neurol 1972,27: 285-91. 13. Norris FH. Neuromuscular transmission in thyroid disease. Ann Intern Med 1966, 64:

81-86 14. Schwartz MS,

Stalberg E. Myasthenia syndrome. Neurology 1975; 25: 80-83.

gravis with features of the

myasthenic

15. Lauritzen M, Smith T, Fischer-Hansen B, Sparup J, Olesen J. Eaton-Lambert syndrome and malignant thymoma Neurology 1980; 30: 634-38. 16. Newsom-Davis J, Pinching AJ, Vincent A, Wilson SG Function of circulating

17

antibody to acetylcholine receptor in myasthenia gravis investigated by plasma exchange. Neurology 1978; 28: 266-72. Kranz H, Caddy DJ, Williams AM, Gay W. Myasthenic syndrome: effect of choline, plasmapheresis and tests for circulating factor. J Neurol Neurosurg Psychiat 1980,

43: 483-88. 18. Vroom FQ, Engel WK. 19. 20.

Non-neoplastic steroid responsive Lambert-Eaton myasthenic syndrome. Neurology 1969; 19: 281. Streib EW, Rothner DA. Eaton-Lambert myasthemc syndrome: long-term treatment of three patients with prednisone Ann Neurol 1980; 8: 121-22. Toyka KV, Drachman DB, Pestronk A, Kao I Myasthenia gravis. passive transfer from

Science 1975; 190: 397-99. K, Engelhardt JK, Fujisawa T, Okamoto T, Katsuki H. A neuromuscular

man to mouse.

21. Ishikawa

block produced by a cancer tissue extract derived from a patient with myasthenic syndrome. Neurology 1977; 27: 140-43. Oh SJ, Kim KW Guanidine hydrochloride in the Eaton-Lambert syndrome. Neurology transmission

the

22.

1973; 23: 1084-90. 23 Blumhardt LD, Joekes AM, Marshall J, Philalithis PE. Guanidine treatment and impaired renal function in the Eaton-Lambert syndrome. Br Med J 1977; i: 946-47 24. Lundh H, Nilsson O, Rosen I 4-aminopyridine - a new drug tested in the treatment of Eaton-Lambert syndrome. JNeurol Neurosurg Psychiat 1977; 40: 1109-112 25. Murray NMF, Newsom-Davis J Treatment with oral 4-aminopyridine in disorders of neuromuscular transmission Neurology 1981; 31: 265-71.